Free Astronomy Magazine March-April 2015

11 ASTROBIOLOGY T his is the stretch of Martian surface on which Nora Noffke believes to have identified the fossil traces left by microor- ganisms that lived on the red planet about 3.5 billion years ago. For more details see next page. [NASA/JPL-Cal- tech/MSSS] I n this video, Nora Noffke, researcher at Old Domin- ion University, Norfolk (Virginia), presents her work, mainly aimed at the study of microbial mats and MISS, and hints at the possibility that these for- mations also exist on Mars. [ODU/Nora Noffke] to distinguish between MISS linked to ma- rine environments rather than lacustrine or fluvial ones, and this also applies to the oldest fossils remnants, which although altered by agents of various nature still re- tain well recognizable details, highly un- likely to replicate through processes in which that sort of symbiosis between sed- imentation and microbiological activity does not occur. And here we go back to the images pro- duced by Curiosity portraying Gillespie Lake Member, because when Noffke ex- amined them she recognized the presence of eroded remnants of MISS of the lacus- trine type: namely, the best that could be hoped to be found in that environment, once located in the shallow waters of a lake. In support of her argument, Nora Noffke indicates the close resemblance of very precise substructures of the possible Mar- tian MISS (from a few centimetres to a few meters in size) with those of some terres- trial MISS, consisting mainly in exfoliations and crumple-ups of thin layers of bio-sed- imentary material (technically chips and roll-ups), cavities more or less wide and deep (pockets and pits), desiccation frac- tures (cracks) and petri- fied gas bubbles (gas domes). But if the simi- larities were just these, Noffke’s hypothesis would not probably be